Added type and value data attributes to SCEngineGotException

darcs-hash:20090225143951-58103-267b631d53b89fdc82c2be3105ce981c31ec5fa8
Only catch SIPCoreError in Session, others should result in a traceback

darcs-hash:20090225144625-58103-83285656803cd14e29451e0a4e18a3fecb728104